1. Field of the Invention
The present invention relates to a refractive index changing apparatus and method.
2. Description of the Related Art
Many researchers have done so far research and development of refractive index changing materials (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-217488). This is because the refractive index determines the propagation characteristic of a light beam, therefore control of a light beam can be realized by controlling the refractive index and spatial distribution of refractive indices. Resulting from the success of the development of refractive index control techniques that utilize liquid crystal, liquid crystal displays have been produced. Moreover, since refractive index changing is regarded as a main technique for optical computers, many researches on secondary or tertiary non-linear optical materials that provide the Pockels effect or Kerr effect have been executed in the field of refractive index changing techniques.
However, most changes in refractive index in a transparent region realized by the secondary or tertiary non-linear optical materials do not substantially exceed 1%. Although liquid crystal achieves a change of about 10% in refractive index, the use of liquid crystal is limited because it is a liquid. Further, when the supply of power to liquid crystal is stopped, records therein disappear.